一、前言
最近项目添加了一项调整应用字体大小功能，做完后空闲之余总结一下。本功能仿照微信应用“设置” - “通用” - “字体大小”功能，又有一点区别。据我所知，常见改变全局字体大小方法有两种，我把这两种分为可控和不可控，为什么这么分呢，当然不是为了方便记忆。那么简单说下两者方式的实现过程：
1、不可控：通过重写Actiivity的getResources()方法更新应用的字体倍数来调整全局字体大小
优点：实现简单
缺点：不可控制（所有字体放大倍数都是一致），无法跨进程（项目中另一个进程的字体不会改变，需要重新配置），只对sp字体单位有效果。....
2、可控：通过setTheme()方法，一开始就初始化设置不同风格的字体样式来更改全局字体大小。
优点：随意调节任意位置的字体大小
缺点：实现麻烦
而本文正式采用了第一种方案，主要是中途添加该功能，时间也不充裕，抽取字体大小又太过耗时。
微信字体大小个人猜测使用第二种方案，后者是更好的实现方式也不一定。
二、效果预览
三、实现步骤
1、自定义字体调整控件
网上找了一个相似的控件并加以完善，功能相对简单，就不做介绍了。
/**
* TODO 仿微信字体大小调整
* 自定义属性：
* lineWidth 线条粗细
* lineColor 线条颜色
* totalCount 线条格数
* circleColor 球型颜色
* circleRadius 球型颜色半径
* textFontColor 文字颜色
* smallSize 小“A” 字体大小
* standerSize “标准” 字体大小
* bigSize 大“A” 字体大小
* defaultPosition 默认位置
*/
public class FontSizeView extends View {
private int defaultLineColor = Color.rgb(33, 33, 33);
private int defaultLineWidth;
private int defaultMax = 5;
private int defaultCircleColor = Color.WHITE;
private int defaultCircleRadius;
// 当前所在位置
private int currentProgress;
// 默认位置
private int defaultPosition = 1;
// 一共有多少格
private int max = 7;
// 线条颜色
private int lineColor = Color.BLACK;
// 线条粗细
private int lineWidth;
//字体颜色
private int textColor = Color.BLACK;
//字体大小
private int smallSize = 14;
private int standerSize = 16;
private int bigSize = 28;
// 圆半径
private int circleRadius;
private int circleColor = Color.WHITE;
// 一段的宽度，根据总宽度和总格数计算得来
private int itemWidth;
// 控件的宽高
private int height;
private int width;
// 画笔
private Paint mLinePaint;
private Paint mTextPaint;
private Paint mText1Paint;
private Paint mText2Paint;
private Paint mCirclePaint;
// 滑动过程中x坐标
private float currentX = 0;
// 有效数据点
private List<Point> points = new ArrayList<>();
private float circleY;
private float textScaleX;
private float text1ScaleX;
private float text2ScaleX;
public FontSizeView(Context context) {
this(context, null);
}
public FontSizeView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context, attrs);
}
private void init(Context context, AttributeSet attrs) {
// initDefault
defaultLineWidth = DensityUtils.dp2px(context, 2);
defaultCircleRadius = DensityUtils.dp2px(context, 35);
lineWidth = DensityUtils.dp2px(context, 1);
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.FontSizeView);
final int N = typedArray.getIndexCount();
for (int i = 0; i < N; i++) {
initCustomAttr(typedArray.getIndex(i), typedArray);
}
typedArray.recycle();
// 初始化画笔
mLinePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mLinePaint.setColor(lineColor);
mLinePaint.setStyle(Paint.Style.FILL_AND_STROKE);
mLinePaint.setStrokeWidth(lineWidth);
//文字画笔
mTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mTextPaint.setColor(textColor);
mTextPaint.setStyle(Paint.Style.FILL_AND_STROKE);
// mTextPaint.setStrokeWidth(DensityUtils.dp2px(context, 1));
mTextPaint.setTextSize(DensityUtils.sp2px(context, smallSize));
textScaleX = mTextPaint.measureText("A");
//文字画笔
mText1Paint = new Paint(Paint.ANTI_ALIAS_FLAG);
mText1Paint.setColor(textColor);
mText1Paint.setStyle(Paint.Style.FILL_AND_STROKE);
mText1Paint.setTextSize(DensityUtils.sp2px(context, bigSize));
text1ScaleX = mText1Paint.measureText("A");
//文字画笔
mText2Paint = new Paint(Paint.ANTI_ALIAS_FLAG);
mText2Paint.setColor(textColor);
mText2Paint.setStyle(Paint.Style.FILL_AND_STROKE);
mText2Paint.setTextSize(DensityUtils.sp2px(context, standerSize));
text2ScaleX = mText2Paint.measureText("标准");
mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mCirclePaint.setColor(circleColor);
mCirclePaint.setStyle(Paint.Style.FILL);
// 设置阴影效果
setLayerType(LAYER_TYPE_SOFTWARE, null);
mCirclePaint.setShadowLayer(2, 0, 0, Color.rgb(33, 33, 33));
}
private void initCustomAttr(int attr, TypedArray typedArray) {
if (attr == R.styleable.FontSizeView_lineColor) {
lineColor = typedArray.getColor(attr, defaultLineColor);
} else if (attr == R.styleable.FontSizeView_circleColor) {
circleColor = typedArray.getColor(attr, defaultCircleColor);
} else if (attr == R.styleable.FontSizeView_lineWidth) {
lineWidth = typedArray.getDimensionPixelSize(attr, defaultLineWidth);
} else if (attr == R.styleable.FontSizeView_circleRadius) {
circleRadius = typedArray.getDimensionPixelSize(attr, defaultCircleRadius);
} else if (attr == R.styleable.FontSizeView_totalCount) {
max = typedArray.getInteger(attr, defaultMax);
} else if (attr == R.styleable.FontSizeView_textFontColor) {
textColor = typedArray.getColor(attr, textColor);
} else if (attr == R.styleable.FontSizeView_smallSize) {
smallSize = typedArray.getInteger(attr, smallSize);
} else if (attr == R.styleable.FontSizeView_standerSize) {
standerSize = typedArray.getInteger(attr, standerSize);
} else if (attr == R.styleable.FontSizeView_bigSize) {
bigSize = typedArray.getInteger(attr, bigSize);
}else if (attr == R.styleable.FontSizeView_defaultPosition) {
defaultPosition = typedArray.getInteger(attr, defaultPosition);
}
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
height = h;
width = w;
circleY = height / 2;
// 横线宽度是总宽度-2个圆的半径
itemWidth = (w - 2 * circleRadius) / max;
// 把可点击点保存起来
for (int i = 0; i <= max; i++) {
points.add(new Point(circleRadius + i * itemWidth, height / 2));
}
//初始刻度
currentX = points.get(defaultPosition).x;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//画字
canvas.drawText("A", points.get(0).x - textScaleX / 2, height / 2 - 50, mTextPaint);
//画字
canvas.drawText("标准", points.get(1).x - text2ScaleX / 2, height / 2 - 50, mText2Paint);
//画字
canvas.drawText("A", points.get(points.size() - 1).x - text1ScaleX / 2, height / 2 - 50, mText1Paint);
// 先画中间的横线
canvas.drawLine(points.get(0).x, height / 2, points.get(points.size() - 1).x, height / 2, mLinePaint);
// 绘制刻度
for (Point point : points) {
canvas.drawLine(point.x + 1, height / 2 - 20, point.x + 1, height / 2 + 20, mLinePaint);
}
// 画圆
if (currentX < circleRadius) {
currentX = circleRadius;
}
if (currentX > width - circleRadius) {
currentX = width - circleRadius;
}
// 实体圆
canvas.drawCircle(currentX + 1, circleY, circleRadius, mCirclePaint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
currentX = event.getX();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
invalidate();
break;
case MotionEvent.ACTION_MOVE:
invalidate();
break;
case MotionEvent.ACTION_UP:
//回到最近的一个刻度点
Point targetPoint = getNearestPoint(currentX);
if (targetPoint != null) {
// 最终
currentX = points.get(currentProgress).x;
invalidate();
}
if (onChangeCallbackListener != null) {
onChangeCallbackListener.onChangeListener(currentProgress);
}
break;
}
return true;
}
/**
* 获取最近的刻度
*/
private Point getNearestPoint(float x) {
for (int i = 0; i < points.size(); i++) {
Point point = points.get(i);
if (Math.abs(point.x - x) < itemWidth / 2) {
currentProgress = i;
return point;
}
}
return null;
}
public void setChangeCallbackListener(OnChangeCallbackListener listener) {
this.onChangeCallbackListener = listener;
}
private OnChangeCallbackListener onChangeCallbackListener;
public interface OnChangeCallbackListener {
void onChangeListener(int position);
}
public void setDefaultPosition(int position){
defaultPosition=position;
if (onChangeCallbackListener != null) {
onChangeCallbackListener.onChangeListener(defaultPosition);
}
invalidate();
}
}
xml使用方式：
<blcs.lwb.lwbtool.View.FontSizeView
android:id="@+id/fsv_font_size"
android:layout_width="wrap_content"
android:layout_height="120dp"
android:layout_marginLeft="@dimen/space_line2"
android:layout_marginRight="@dimen/space_line2"
android:background="@color/white"
app:circleRadius="11dp"
app:lineColor="@color/round_corner_progress_bar_progress_default"
app:standerSize="16" />
2、滑动按钮改变当前页面预览字体大小
//备注
<!--字体大小 及倍数-->
<!--0.875=14/16 -->
<dimen name="sp_small">14sp</dimen>
<!--1 标准-->
<dimen name="sp_stander">16sp</dimen>
<!--1.125=18/16-->
<dimen name="sp_big1">18sp</dimen>
<!--1.25=20/16-->
<dimen name="sp_big2">20sp</dimen>
<!--1.375=22/16-->
<dimen name="sp_big3">22sp</dimen>
<!--1.5=24/16-->
<dimen name="sp_big4">24sp</dimen>
<!--1.625=26/16-->
<dimen name="sp_big5">26sp</dimen>
<!--1.75=28/16-->
<dimen name="sp_big6">28sp</dimen>
//滑动返回监听
fsvFontSize.setChangeCallbackListener(new FontSizeView.OnChangeCallbackListener() {
@Override
public void onChangeListener(int position) {
int dimension = getResources().getDimensionPixelSize(R.dimen.sp_stander);
//根据position 获取字体倍数
fontSizeScale = (float) (0.875 + 0.125 * position);
//放大后的sp单位
double v = fontSizeScale * (int) DensityUtils.px2sp(FontSizeActivity.this, dimension);
//改变当前页面大小
changeTextSize((int) v);
}
});
/**
* 改变textsize 大小
*/
private void changeTextSize(int dimension) {
tv_font_size1.setTextSize(dimension);
tv_font_size2.setTextSize(dimension);
tv_font_size3.setTextSize(dimension);
}
3、返回时，保存放大倍数并重启应用
public void onClick(View view) {
SPUtils.put(FontSizeActivity.this,Constants.SP_FontScale,fontSizeScale);
//重启应用
AppManager.getAppManager().finishAllActivity();
IntentUtils.toActivity(FontSizeActivity.this, MainActivity.class,true);
}
4、初始化应用时配置字体放大倍数。
改变全局大小的关键 //
res.updateConfiguration(config,res.getDisplayMetrics());
//fontSizeScale = (float) SPUtils.get(this, Constants.SP_FontScale, 0.0f);
@Override
public Resources getResources() {
Resources res =super.getResources();
Configuration config = res.getConfiguration();
if(fontSizeScale>0.5){//防止第一次获取SP时得到默认值0
config.fontScale= fontSizeScale;//设置正常字体大小的倍数
}
res.updateConfiguration(config,res.getDisplayMetrics());
return res;
}
源码地址：
https://github.com/DayorNight/BLCS
到这里就结束啦。
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